Items to be controlled the quality in spot welding
Welding current control
- 1.Upper and lower-limit values of welding current setting
- To create control standard that welding current must be determined specifically.
- 2.Mounting of an interlock
- If more than two welding machines are energized simultaneously, power supply voltage(400V or 200V in general) of factory is down. It may happen that the voltage can’t maintain lower-limit values of welding current. To prevent it, mount interlocking device, which can control energization in order by receiving terminal signal. So, until a welding machine receiving conduction signal earlier is finished, another machines can’t be energized.
- 3.Usage of constant current controller
- To use a timer with guarantee function that set welding current flows any time.
- 4.Usage of controller with step-up function
- To use a timer with function which escalates welding current gradually, as expansion of tip diameter of current,
Electrode force control
- 1.Mounting of pressure monitor
- To mount a monitor which sends attention signal when it detects a reference pressure not higher than a limit pressure, in case the pressure of factory compressor decreases.
- 2.To perform regular hysteresis measurement of electrode force
- The friction of cylinder part becomes large as the machine gets used up. Quick response of vertical movement of electrode deteriorates, electrode force becomes higher. Consequently, poor weld happens.
Energizing time control
To inspect energizing time error of timer regularly by welding current meter. And setup to send signal, in case it detects something except a reference range.
Electrode shape
- 1.Electrode dressing and replacement time
- To determine electrode dressing and estimated replacement time of electrode tip in advance due to the welding operation content, perform those safely.
- 2.Dressing method of electrode tip
- To determine dressing method of electrode tip to maintain same tip diameter of electrode.
Water cooling control
Cooling electrode will significantly affect the lifetime of electrode.
To keep cooling water temperature 10～30℃, control flow rates of 2～3 liters per minute for each electrode tip. Be sure whether a water cooling tube cap of electrode content is 5～10mm.
What is necessary measurement instrument for quality control?
Whenever you can watch on a welding current, a welding force, and an energizing time, measurement instrument should be always ready to use, as significant control items of welding condition.
・Welding current,Energizing time→Welding current meter
・Welding pressure→Pressure meter
You should use welding current meter definitely when starting the work to confirm set welding current and energizing time.
It is desirable to perform hysteresis measurement of electrode force at the time of purchase of the welding machine and semiannually.